Production of nanocrystalline metal powders using the wire explosion techniques
Abstract
It is anticipated that the use of ultrafine metal powders of nanocrystalline structure may lead to p/m components with new and yet unknown properties. Therefore much effort is spent at present to develop processes for the production of such powders. In this research it was investigated whether the wire explosion technique is suitable for this purpose. This process uses the energy of an electric current pulse to melt or vaporize a wire consisting of the material to be powderized. The wire is contained in a pressure vessel, where an inert gas atmosphere serves as the energy sink for the solidifying and condensing material. Parameters investigated were material, wire dimensions, voltage and gas pressure. TEM work was used to characterize the particles obtained. The results showed that under certain conditions very fine powders of metallic elements and alloys could be obtained in small quantities. The particles were of spherical or non-spherical shape and less than 50 nm in diameter. Gener ally, they revealed an even finer granular substructure of only a few Nanometers. The conditions of formation of the structure observed are discussed in detail.
